Synchronizing apparatus



June 1-7, 1941. ARTzT 2,246,284

SYNCHRONIZING APPARATUS Filed July 26, 1938 Buck PRINTER "Co/L WHITE PRINTER COIL INVENTOR. MAURICE ARTZT ATTORNEY.

Patented June 1?, i941 srscnnomznro APPARATUS MauriceArtzt, Haddorifield, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application July 26, 1938, Serial No. 221,299

- e 7 Claims. My invention relates in general to apparatus for maintaining two or more driven machines in type of synchronous arrangements used, the prime mover or motor which operated the machine could very easily stop on dead center, that is to say,- that the machine might assume such a position when stopped that synchronizing signals would not complete the driving motor energizing arrangem'ent, and hence a severe disadvantage occurs. t

Accordingly, it is one of the objects of this invention to provide an arrangement whereby the drivingmotor may be energized and maintained synchronously operating regardless of the relative positions oi the apparatus when stopped. Again, in at least one of the better known synchronizing arrangements, the driving motor is "jog at regular intervals unless a synchroniz ing signal is received which prevents such jo'gging. The phenomenon oi iading mayeasily prevent the receipt of such a signal, and hence while the machine may be in exact synchronism, nevertheless, the motor will be jogged due to the fact that no synchronizing signal actually has been received to prevent this occurrence, and as a result the machine actually may be thrown out of synchronizing relationship with the scanner in the case 01 facsimile on. Accordingly. it is another of the objects of my invention to provide a device whereby synchronous relationship may be maintained even it some of the synchronizing signals are not received, provided the signals trans; v

mitted are of maximum amplitude for white.

Again, in the arrangement shown in the prior art, the synchronizing apparatus per se has been somewhat diflcult to adjust, assemble and maintain correct adjustment. Accordingly, it is another of the objects oimy invention to provide a arrangement which is both sim-- pie, accurate, and easyto adjust.

round that due to.

Furthermore, it has been varying characteristics of motors in so far; as slippage is concerned, one motor may slipa great deal more easily than another, this effect being caused by tight bearings or, in the case of a motor that has low slip, the bearings will be loose. Some way should be provided to take care or this when stopped.

slipping function and, accordingly, it is another of the objects of my invention to provide an apparatus whereby the characteristics of any motor may be adequately compensated so as toprovide a definite pole slipping function.v In this respect, this invention comprises an improvement on the arrangement disclosed in the co-pending application entitled Synchronizing apparatus, Serial No. 221,300, filed concurrently herewith by Mr. C. J. Young. 7

Similarly, a vacuum tube with age may change its characteristics, and also since probably no two vacuum tubes even oi. the same type have identical characteristics, some compensatory measures should be used in order to assure definite and adequate synchronizing influence. Accordingly, it is another of the objects or my invention to provide an arrangement in which this is done.

Therefore, the objects or my invention are:

1. To provide an arrangement whereby the driving motor in a facsimile 'recorder may be energized and'maintained synchronously operating regardless of the relative positions of the apparatus 2. To provide a device whereby synchronous relationship may be maintained even it some or the synchronizing signals are not received in a signal on white system. I -3. To. provide a synchronizing arrangement which is both simple, accurate, and easy to adjust. 4. To provide an arrangement for compensating for the varying pole slipping characteristics or any driving motor in a machine 0! this nature.

5. To provide an arrangement wherein the varying characteristic of a vacuum tube with age, or. of

tice to place an image to be transmitted onto a V drum known as the scanner drum, and asthis drum is rotated electrical impulses are developed sequentially which are representative or the optical values along each linear strip oi. the image.

-' Since, necessarily, the'reconstruction oi the tac-v in order to'reconstruct a true facsimile. One such simile oi the optical image must be made line by. line, the material on which the image is to be recorded is usually passed around, or adjacent to, a recording drum which must operate synchro-' nously with the movement of the scanner drum In this patent, there is disclosed a recorder drum around which is provided a single turn helix. Adjacent the helix is positioned a presser bar, and between the presser bar and the helix there is passed a material on which the image may be recorded and a sheet of carbon paper, and the action of the presser bar is such as to leave a smudge of elementary area on the recording material where the bar strikes the helix. For more detailed information reference should be had to that patent.

The receiver for such a device is provided with two tubes, a so-called black tube and a so-called white tube. The black tube conducts when the said incoming signals are representative of black in the picture, and continues to conduct well up in to the white section of the picture. On the other hand, the white tube does not begin to conduct until currents representative of a medium value of white are impressed thereon, and the action of these two tubes taken conjointly is such as to give a. desirable. linear, or accentuated, operation in reconstructing the picture. This arrangement per se is not the entire subject-matter of this invention, and reference should be had to my co-pending application Serial No. 737,720, filed July 31, 1934, showing such an arrangement.

Now, in accordance with my invention, synchronizing impulses are transmitted in a black sense. There is joined to the recorder in an appropriate position, either directly connected to the commutating segment. These brushes are ad,-

justable. Two of the brushes form a part of a relay energizing circuit, and the third brush has a function which will be hereinafter explained. The relay is connected in the output circuit of a tube which is biased so that it is responsive to picture signals andto the synchronizing signals.

' thus the relay is held in a locked position as long as the third brush is in contact with the commutating segment.

.The third brush hereinbefore referred to is located at the lower and hence longer part of the L-shape segment and, therefore, the relay will remain closed or locked longer than the period during which the plate current alone of the white" tube would keep the relay closed. As this brush is adjustable, the locking time and hence the time that the motor energizing circuit remains open is a function of the position of this brush with respect to the commutating segment and the other brushes. Hence, any variation in slippage in the motor may be compensated.

Again, the resistors through which the relay winding is energized being variable in nature,

. compensation for the variations in the characteristic of the vacuum tubes may be adequately pensated.

My invention will best be understood by reference to the drawing in which the single figure thereof shows one embodiment of my invention.

Referring to the figure, there are shown two vacuum tubes I and 2 having anode, cathode, control and screen electrodes. Tube I is appropriately biased so that it is conducting when signals are impressed on the control grid thereof which represent from lower black to medium grey or up into the light section of a transmitted picture. Tube 2 is appropriately biased and operated so that it does not respond to signals in the com- lower black region but begins to take hold, so-tospeak, when the signals representative, for in Thus when the commutating segment closes the be energized. This relay then performs a dual function.

Adjacent the relay are a pair of contact members and a pair of armature members, the latter which may be interlocked. If the machine be out of'synchronism and the relay is energized, one contact which is normally closed with one armature will be opened, and this contact and armature being in the driving motor circuit, it willcause a' jogging of the motor.

Simultaneously, the second armature will be pulled down into contact with the second contact member, the latter being joined to the aforementioned third brush, This then places the energizing voltage for the plates of the white and black tubes substantially in parallel with} the relay through appropriate resistance members, and

stance, of grey are impressed on the control grid substantially linear response, or the response may be accentuated as desired.

Connected in the anode circuit of tube I, as shown in the drawing, is one of the coils 3 which adapted to actuate the presser bar and which is identified in the drawingv as the black printer coil. Similarly connected in the anode circuit of tube 2 is a further coil which is adapted to actuate the presser bar hereinbefore referred to and which is identified as the white printer coil.v

- The screen grids in this instance are connected .together and to the anode and a source of positive J negative side of this source of energy is grounded.

A potentiometer I is connected in parallel with the source of energy for the anodes of the tubes. The movable terminal 6 of this source of energy is connected through a relay winding I to one brush 8. A second brush 9 which is adjacent brush 8 is then connected to the anode of the white tube. Positioned immediately adjacent the core of the relay winding I is an armature II which may be mechanically coupled with a second armature ll so that the action of the two is simultaneous. A contact I! is normally held in engagement with the armature Ill, and this arrangement forms a switch which is connected, in series with the energizing circuit of the prime v with armature II, that is parallel with armature Ii which is normally retracted with respect thereto. Connected in series with contact l3 and the armature ii is a resistor I4 which is grounded at the extremity opposite this connection.

Also connectedin series with the armature ll nous relationship, what is meant is not only that and the contact i 3 is a third brush i5 which is are adjustable with respect to the commutating disc and to each other. v

The operation of the device is as follows: During the interval that the synchronizing signal is sent, current will flow only in the "black tube in view of the fact that the white" tube does not conduct for currents representng a black" value and, as has been hereinbefore stated, thesynchronizing signal is transmitted in the blac sense.

For synchronous operation of the machine, the conducting segment comes into a position whereby brushes 8 and 9 are connected together by the segment at the interval that the synchronizing signal is transmitted. Since' these brushes are connected through the relay energizing coil across the white" printer coil, no current will fiow through the relay coil 7 during the receipt of the synchronizing signal and, as a result, the armature l0 and the contactor will remain closed and thus the energizing circuit for the driving motor is unaffected.

However, should the machine not be in synchronism, the segment 20 will not connect the brushes 8 and Sat a time when the synchroniz ing signal arrives and, as a result, when the segment 20 does close the brushes, signals representative'of a picture line are being received and hence have white components. This means then that the white tube will be conducting. Hence, therelay coil I will beenergized sufiicient to flutter the armatures l0 and I i, and the armatures Ill and II will be drawn toward the core of the relay which opens the motor circuit for a short interval of time. When the armature H, which is normally retained in a retracted position with respect to contactor [3 comes into contact with the member 13, the resistor, brush l5, relay coil 1 and a portion of resistor 5 are connected in series. This means then that as long as the brush i5 is in conducting relationship with the segment 29, the relay coil I will be energized 'be definitely adjusted to fit any slippage conditions of any particular driving motor. In view of the fact that the locking system operates irom the potential drop across a portion of resistor 5 as taken off by the potentiometer-moving contact ,8, this potential may be soadjusted that changing characteristics of any tube, or difierent tubes, may be adequately compensated.

It should be understood that when I speak of the scanner and recorder operating in synchroto at least within the grey portion of the picture,

the driving motors are running at equal speeds, but that the scanner drum and the recorder drum are being operated in'phase.

It also should be understoodthat whenI speak of transmission on white, I mean that the signal amplitude increases as the scanned picture point gets lighter in shade. A signal on a black" system naturally would be the reverse.

It will be appreciated that there may be a number of departures which are within the spirit and scope of myinvention and, accordingly, I am not limited to the specific embodiment except as identified in the following claims.

What I claim is:

1. An apparatus for maintaining a facsimile scanner and at least one recorder in synchronous relationship each with the other and wherein synchronlzing signals corresponding to picture black and indicative of the position or said scannerfiand picture signal are transmitted comprising'meansfor receiving said signals, a first thermionic amplifying means responsive in a range from black 9. second thermionic amplifying means responsive from a range of white to at least within the grey section 01' the picture but which is without the range 01 black, a motor, a source of energy for driving said motor, a commutator operable by said motor, the position of said commutator being such that it is at a predetermined position when said synchronizing signals are received when .running synchronously with the scanner, means mutating segment, and means for locking said -actuating means for a predeterminable interval of time. 1

2. An apparatus for synchronizing a facsimile.

scanning device and at least one recorder and wherein electrical synchronizing impulses corresponding to black and indicative of the operating position of the scanner and picture impulses are transmitted comprising means for receiving said impulses, a first thermionic amplifier responsive to electrical impulses representative of black, a second thermionic amplifier biased normally to a non-conducting state during the receipt oi black impulses and responsive to picture signals,

meansior impressing said picture and synchro- 1 nizing signals onto the input circuit of said thermionic amplifiers, a driving motor for said recorder, a source ofenergy for said driving motor, a commutator operated-by said driving motor and positioned so as to attain a definite position when said machines are operating synchronously, a pair ofbrush members positioned adjacent to and'ln contact with said commutator during a portion of pair of brushes go from a conducting relationship with respect to said commutator.

3. An apparatus for synchronizing a facsimile to an insulating relationship scanning device and atleast one'recorder and wherein! electrical synchronizing impulses corresponding to black andindicative of the operatingposition of the scanner and picture impulses are transmitted comprising means for receiving said impulses, a first thermionic amplifier responsive to electrical impulses representative of black, a second thermionic amplifier biased normally to a non-conducting state during thereceipt of black impulses and responsive to picture signals, means for impressing said picture and synchronizing signals onto the-input circuit oi said thermionic amplifiers, a driving motor for said recorder, a

source of energy for said driving motor, a commutator operated by said driving motor and posi-' armatures normally being held. in a position touching one of said contacts and the second of said armatures being positioned so as to be normally retracted from contact with the second or said contacts, the first armature and contact member being connected in series in the motor energizing circuit, a third brush positioned adjacent said commutating segment and adapted to be in contact therewith during at least a part of the time that one of the pair or contact members is in. contact with said segment, and means for Joining said third brush memberto the negative of the energy for said thermionic tubes.

4. Apparatus in accordance with claim 3 wherein said commutator is an L-shaped conductor and wherein a variable resistor is provided in series with the relay coil.

5. Apparatus in accordance with claim 1, wherein said commutating segment comprises an L- shaped conducting member. I

6. Apparatus in accordance with claim 1, wherein said commutating segment comprises an L-shaped member, and wherein the means for controlling the actuating means positioned ad- Jacent said commutating segment comprise a plurality of brush members for co-actingwith said segment.

segment, and wherein the position or said brushes 7 is adjustable with respect to said segment.

MAURICE ARTZT. 

